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초고압 소결된 다이아몬드/실리콘 카바이드 복합재료의 계면특성 및 기계적 특성
박희섭,류민호,홍순형,Park, Hee-Sub,Ryoo, Min-Ho,Hong, Soon-Hyung 한국분말야금학회 2009 한국분말재료학회지 (KPMI) Vol.16 No.6
Diamond/SiC composites are appropriate candidate materials for heat conduction as well as high temperature abrasive materials because they do not form liquid phase at high temperature. Diamond/SiC composite consists of diamond particles embedded in a SiC binding matrix. SiC is a hard material with strong covalent bonds having similar structure and thermal expansion with diamond. Interfacial reaction plays an important role in diamond/SiC composites. Diamond/SiC composites were fabricated by high temperature and high pressure (HPHT) sintering with different diamond content, single diamond particle size and bi-modal diamond particle size, and also the effects of composition of diamond and silicon on microstructure, mechanical properties and thermal properties of diamond/SiC composite were investigated. The critical factors influencing the dynamics of reaction between diamond and silicon, such as graphitization process and phase composition, were characterized. Key factor to enhance mechanical and thermal properties of diamond/SiC composites is to keep strong interfacial bonding at diamond/SiC composites and homogeneous dispersion of diamond particles in SiC matrix.
초 고온·고압 소결 공정으로 제조된 다결정 다이아몬드 컴팩트(PDC)의 미세조직 및 열충격 특성에 미치는 다이아몬드 입자 비율의 영향
김지원,박희섭,조진현,이기안,Kim, Ji-Won,Park, Hee-Sub,Cho, Jin-Hyeon,Lee, Kee-Ahn 한국분말야금학회 2015 한국분말재료학회지 (KPMI) Vol.22 No.2
This study investigates the microstructure and thermal shock properties of polycrystalline diamond compact (PDC) produced by the high-temperature, high-pressure (HPHT) process. The diamond used for the investigation features a $12{\sim}22{\mu}m$- and $8{\sim}16{\mu}m$-sized main particles, and $1{\sim}2{\mu}m$-sized filler particles. The filler particle ratio is adjusted up to 5~31% to produce a mixed particle, and then the tap density is measured. The measurement finds that as the filler particle ratio increases, the tap density value continuously increases, but at 23% or greater, it reduces by a small margin. The mixed particle described above undergoes an HPHT sintering process. Observation of PDC microstructures reveals that the filler particle ratio with high tap density value increases direct bonding among diamond particles, Co distribution becomes even, and the Co and W fraction also decreases. The produced PDC undergoes thermal shock tests with two temperature conditions of 820 and 830, and the results reveals that PDC with smaller filler particle ratio and low tap density value easily produces cracks, while PDC with high tap density value that contributes in increased direct bonding along with the higher diamond content results in improved thermal shock properties.
다결정 다이아몬드 컴팩트(PDC)의 미세조직 및 내마모 특성에 미치는 초기 성형 압력의 영향
김지원,박희섭,조진현,이기안,Kim, Ji-Won,Park, Hee-Sub,Cho, Jin-Hyeon,Lee, Kee-Ahn 한국분말야금학회 2015 한국분말재료학회지 (KPMI) Vol.22 No.3
This study investigated the microstructure and wear resistance property of HPHT(high pressure high temperature) sintered PDC(polycrystalline diamond compact) in accordance with initial molding pressure. After quantifying an identical amount of diamond powder, the powder was inserted in top of WC-Co sintered material, and molded under four different pressure conditions (50, 100, 150, $200kgf/cm^2$). The obtained diamond compact underwent sintering in high pressure, high temperature conditions. In the case of the $50kgf/cm^2$ initial molding pressure condition, cracks were formed on the surface of PDC. On the other hand, PDCs obtained from $100{\sim}200kgf/cm^2$ initial molding pressure conditions showed a meticulous structure. As molding pressure increased, low Co composition within PDC was detected. A wear resistance test was performed on the PDC, and the $200kgf/cm^2$ condition PDC showed the highest wear resistance property.
초 고온·고압 소결 공정으로 제조된 다결정 다이아몬드 컴팩트의 열충격 특성에 미치는 다이아몬드 입자 크기의 영향
김지원,백민석,박희섭,조진현,이기안,Kim, Ji-Won,Baek, Min-Seok,Park, Hee-Sub,Cho, Jin-Hyeon,Lee, Kee-Ahn 한국분말야금학회 2016 한국분말재료학회지 (KPMI) Vol.23 No.5
This study investigates the thermal shock property of a polycrystalline diamond compact (PDC) produced by a high-pressure, high-temperature (HPHT) sintering process. Three kinds of PDCs are manufactured by the HPHT sintering process using different particle sizes of the initial diamond powders: $8-16{\mu}m$ ($D50=4.3{\mu}m$), $10-20{\mu}m$ ($D50=6.92{\mu}m$), and $12-22{\mu}m$ ($D50=8.94{\mu}m$). The microstructure observation results for the manufactured PDCs reveal that elemental Co and W are present along the interface of the diamond particles. The fractions of Co and WC in the PDC increase as the initial particle size decreases. The manufactured PDCs are subjected to thermal shock tests at two temperatures of $780^{\circ}C$ and $830^{\circ}C$. The results reveal that the PDC with a smaller particle size of diamond easily produces microscale thermal cracks. This is mainly because of the abundant presence of Co and WC phases along the diamond interface and the easy formation of Co-based (CoO, $Co_3O_4$) and W-based ($WO_2$) oxides in the PDC using smaller diamond particles. The microstructural factors for controlling the thermal shock property of PDC material are also discussed.
초 고온·고압 소결된 다결정 다이아몬드 컴팩트의 미세조직 및 마모 특성에 미치는 다이아몬드 입자 크기의 영향
백민석 ( Min-seok Baek ),박희섭 ( Hee-sub Park ),이재일 ( Jae-il Lee ),이기안 ( Kee-ahn Lee ) 대한금속ㆍ재료학회 2017 대한금속·재료학회지 Vol.55 No.11
A polycrystalline diamond compact (PDC) is a two-stage sintered body manufactured by placing diamond powders on a WC-Co hard material and then applying the high pressure high temperature (HPHT) sintering process. This study investigated the microstructure and wear properties of the PDC depending on initial diamond particle size. Three different sizes (12-22 μm, 10-20 μm, and 8-16 μm) of initial diamond powders were used to manufacture PDCs with the HPHT sintering process. Some Co and WC were observed along the boundaries between the diamond particles in the three manufactured PDCs. The diamond layer formed using small diamond particles showed finer and more even area distribution of Co along the diamond particles. VTL equipment was used to conduct a granite cutting wear test. The result confirmed that smaller initial diamond particle size leads to greater wear resistance properties. Observation of the PDC wear surface confirmed that the PDC made with larger diamond particles was more prone to be weak along the boundaries between the diamond particles, and there were instances where the diamond particles were displaced as a whole. For PDCs of smaller diamond particle size, abrasive wear occurred where the diamond particles were gradually worn away. (Received July 19, 2017; Accepted July 26, 2017)